Rock drill



Nov. 20, 1951 J. s. Roaams 2,575,975

ROCK DRILL Filed April 1, 1950 IINVENTOR: I JAMES S. ROBBlNS a BY ATT'YS Patented Nov. 20, 1951 UNITED STATES PATENT OFFICE ROCK DRILL James s. Robbins, Highland Park, In.

Application April 1, 1950, Serial No. 153,335

2 Claims.

This invention relates to rock boring devices and particularly to a type of calyx drills for use in rock materials, such as coal, which are friable and can be most rapidly bored by combining kerf cutting and core breaking operations in displacing material during the boring operation.

The main objects of this invention are to provide an improved form of boring device which is capable of removing friable rock in comparatively large pieces; to provide an improved form of calyx drill which is capable of simultaneously cutting concentric kerfs in the face of a rock wall and then breaking down the cores that stand between such kerfs by a wedging action; and to provide an improved drill of this type that is both eflicient in operation and durable in construction.

A specific embodiment of this invention is shown in the accompanying drawings in which:

Figure l is a top plan of a drill head constructed according to this invention; and

Fig. 2 is a side elevation of the same with parts thereof shown in section on the line 2--2 of Fig. 1.

In the form shown in the drawings, the head 5 comprises a top portion 6 in the form of a tapered threaded nipple and a lower portion 1 of conical form tapering downwardly and having attached at its lower end a pilot bit 8 in axial alinement with the nipple and conical surfaces of the head 5.

Adjacent the upper part of the conical member 1 are a plurality of radially disposed spider arms 9 to the outer ends of which is attached a cylindrical calyx drill body Ill and one or more intermediate cylindrical calyx drill bodies II. Each of these calyx drill bodies has a series of teeth I2 and I3 respectively formed on its lower periphery and these teeth are equipped with cutters I4 of hard material. The calyx drill bodies I and II are partly cut away to provide spaces I5 between their teeth and spaces I6 at their upper ends to permit the free passage of cuttings and rock fragments.

It will be seen from the drawings that the pilot bit 8 extends in advance of the calyx cutters and effectively guides its direction of movement and that the teeth I2 and I3 of the calyx cutters cut kerfs in the rock face concentric with the axis of the pilot bit. The shape of the cuts in the rock wall is generally indicated by the uneven line I! in Fig. 2 and from which it is seen to comprise a central bore I8, an external kerf I9 that defines the outside diameter of the bore and an intermediate kerf 20.

As shown in Fig. 2, the toothed end of the inner cylindrical cutter l I is located rearward of the cutting end of the pilot bit 8, and the toothed end of the outercylindrical cutter I0 is located rearward of the cutting, or toothed, end of the inner cylindrical cutter The conical portion I is flared rearwardly and outwardly from a point rearward of the cutters I3 of the inner cylindrical cutter II. Similarly the inner cylindrical cutter II has associated therewith members 2| that flare rearwardly and outwardly from a point rearward of the cutting teeth |2 of the outer cylindrical cutter ID to a point rearward of the body of the cutter Ill.

The conical portion I of the head serves as a wedge for exerting outward pressure upon the annular core of rock that is formed between the bore I8 and the kerf 20. Similarly, the upper end of the intermediate cylindrical body II is connected to the arms 9 by a wedge formation generally of conical form flaring upwardly and outwardly for breaking down the core of material formed between the kerfs 20 and I9. The parts 2| are of conoidal outer contour and, due: to their downward and rotary motion, break down the core of material in the same manner as: is done by the cone I. As shown, the parts 2| lie in a common conical surface concentric with the axis of cone I but the intermediate portions of such conical surface are omitted to provide clearance spaces between them for the passage of broken rock. A spiral screw rib 22 formed on the surface of the cone I tends to draw the cone into the bore l8 and helps to break down the core of rock 23. The conical surface defined by the parts 2| is similarly ribbed with a spiral rib or flange 22.|. These ribs are each preferably formed with constant pitch but increase depth from their lower to their upper ends.

In operation, the pilot bit directs the forward travel under the pressure exerted by the weight of the device and its operating stem or by pressure applied to the stem as will be understood; the calyx cutters l0 and II cut kerfs concentric with the bore I8 and the concentric cores 23 and 24 are then broken by outward pressure of the conical members I and 2|.

The fragments of broken rock pass upward through the spaces between the spider arms 9 and are removed from the bore ll by floatation with drilling mud or otherwise as is well known in this art.

The stem of the device shown is hollow and the head has passages 25, 26 and 21 for discharge of liquid or semiliquid boring fluids.

Although but one specific embodiment of this invention'is. herein shown and described, it will be understood that numerous details of the structure shown may be altered or omitted 'Without departing from the spirit of the invention as defined by the following claims:

I claim:

1. A rock drill, comprising a head, a drill bit mounted thereon in axial alinement therewith, an inner cylindrical shell spaced concentrically outward fromsaid'bit' and having:a toothedicutting edge spaced axially rearward of the cutting end of said bit, said head having a wedging surface flaring rearwardly and outwardly from a point rearward of the cutting edgewof said shell to a point rearward of said shell, an outer cylindrical shell spaced concentrically from said inner shell and having =a toothe,d,cut ting edge spaced axially rearward of the cutting edge of said inner shell, wedge meanssspaced,

radially outward from said head and positioned to follow said inner shell into a -=rock kerf cut thereby and having a conoidal surface "inclined outwardly andrearwardlyfrom said inner-shell so as to exertradially outwardly directed'lpressure against the core or"rock-standing-between 25 said shells, and means connecting said shells and wedge means to said head.

-2. A rock drill, comprising a head, "adrillwbit mounted thereon in axial alinement therewith,

said head having a conoidal wedge surface flaring backwardly and outwardly from the path of said bit and having a spirally ribbed formation, inner and outer cylindrical cutter shells spacedapart concentrically at different radial distances for cutting concentric kerfs in an opposed rock face, spider arms connecting said shells to said head. conoidal wedge members carried on said arms behind said inner shell substantially parallel with and .spacdiradiallycoutward from said firstmen'tiondconoidal wedge""surfa'ce to bear upon and break outwardly a coreof rock formed be- -'-'tween the kerfs cut by said shells, and spiral :screw ribs on the outer side surfaces of said lastnamed wedge member.

7 JAMES S. ROBBINS.

REFERENCES CITED The following references are of record in the file of this --paten-t: V

UNITED STATES PATENTS .Number .Name Date 265,500 Herron Oct. 3 3, 11882 "795,433 "'Foust July 25,1905 1,572,386 Gates Feb. 9; 1926 1,831,841 Brantly Nov.17,'1931 2,161,000 Andersen June "6, I939 

